Abnormal feather-like grains induced by the thin-wall effect in a polycrystalline nickel-based superalloy

•Abnormal feather-like grains with high-angle grain boundaries were detected in a thin-walled polycrystalline superalloy.•The quantity of the feather-like recrystallized grains was increased with the decrease of the specimen thickness.•The formation mechanism of the abnormal feather-like grains was revealed.